Method for desiccation



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W. L. FLEESHER METHOD FOR DESICCA'I'ION Filed Feb. 3. 1922 FAN HEATER TU DUST Gal-L.

INVENTOR \MLF'LEIISHER.

ATTORNEY Patented Oct. 21, 1924.

UNITED STATES WALTER. L. FLEISHER, or NEW YORK, N. Y.

METHOD FOR DESICCATION.

Application filed February 2, 1921. 'Serial No. 441,930.

To all whom it may concern:

Be it known that I, WALTER L. FLEIsHER, a citizen oi; the United States, and a resident of the county of New York, city and State of New York, have invented a new Method for Desiccation, of which the following is a full, clear, and exact description.

An object of the invention is to provide a simple, inexpensive and efficient method for desiccation of substances which can be sprayed.

The drying or desiccating agent, in my method, is a warm air current circulated to form continuous, oppositely directed interconnected moving air currents, and which currents form substantially a hollow cylinder into which the substance to be desiccated is atomized so that it tends to intersect the oppositely moving portions of the interconnected air currents. The circulation of the drying agent is so regulated within the spray chamber that the air may be caused to make one or more revolutions or turns before it is allowed to escape from the spray chamber. This arrangement increases the efliciency of the method.

In my method of spray drying, the air is so circulated that the hottest or driest air contacts with that part of the sprayed substance which has already been in contact with air not so hot or dry. In other words, the hottest or driest air in my arrangement acts on partially dried particles of the spray, in consequence case hardening of the particles is prevented. .Further than that, the air that has already absorbed some of the moisture from the particles, as it approaches its exit, strikes the spray nearer the nozzles by means of which the spray is introduced into the spray chamber, and, in consequence, the dust that is carried by the eflluent air is washed down, thereby reducing considerably the dust in the effluent air, and helping to increase the size of the particles formed within the spray drier.

In the accompanying drawing, forming part of the application, Figure 1 represents a diagrammatic sectional view through a form of apparatus suitable for carrying out my method, and

Figure 2 shows a vertical section through Figure 1 on line 22.

Referring to the drawing, 3 is a desiccating chamber which has an elongated air inacross the entire chamber (see let 4, preferably extend ng substantially Figure 2) and located preferably in proximity to the bottom of the chamber. The inlet 4 enters the chamber at an angle to the horizontal (see F igure 1) so as to direct the entering air current at an angle to the horizontal, (preferably the current is deflected upward) so as to reduce the downward deflection of the entering current by the induced current formed between the inlet 4 and the main outlet 5, the said outlet extending substantially through the entire width of the chamber and located in proximity of the inlet 4 and above the same. A direct rise of the air from the inlet to the outlet is prevented by the velocity imparted to the entering air layer which causes the said layer to shape itself substantially in the form outlinedby arrows in Figure 1, between the inlet and the main outlet.

The thickness of the air layer forming the wall of the hollow air cylinder within the chamber 3 varies from the inlet to the outlet due to the sudden expansion of the entering air layer within the spray chamber and the subsequent contraction of the said air layer when it leaves the chamber 3 through the main outlet 5. Due to the expansion of the air within the chamber 3 the velocity of the air layer atthe inlet and at the outlet is greater than at any point between the two, the minimum velocity of the air layer being in the most expanded part of the air layer.

The chamber 3 has means for controlling the intensity of the induced current in-the gap 14 formed by the inlet 4 and the main outlet 5. The said means are in the form of an auxiliary air outlet 6 located in proximity or at the top of the chamber 3 and extending substantially through the entire width of the chamber.

The auxiliary air outlet 6 and the main air outlet 5 unite in a suitable conduit 7 which leads to the dust collecting chamber not shown, as it does not form part of the invention.

As will be noted, in a rectangular chamber, the air inlets and the air outlets are located at the same side of the chamber, but in a drumlike chamber where there is no side, the relation of the inlets and the out lets remains the same as shown.

A series of nozzles 8 enter the chamber 3 between the'outlets 5 and 6. The entering nozzles are disposed in a horizontal row above the outlet 5 and substantially parallel therewith. The row of nozzles is adapted .in combination to produce a flat sheet of the atomized substance at an angle to the horizontal and preferably directed downward to enter the hollow cylinder formed by the drying air current within the chamber 3 (see Figure 1).

The spray enters the hollow cylinder in a plane passing substantially through the elements of the cylinder, and the direction of the spray is substantially at right angles to the elements of the hollow cylinder.

The air current striking the entering spray causes a deflection of the spray as it pene trates into the air current. The particles that pass across the hollow of the cylinder are picked up by the oppositely moving currents and carried toward the spray nozzles where their size is increased by the contact with the spray entering the air current.

The air current is forced through the inlet 1 into the chamber 3 by a fan 9 which fan draws the air through a suitable heater 10. The air entering the chamber at a high velocity is forced by the fan towards the wall opposite the inlet 4, which Wall aids the current to deflect upwardly toward the top of the chamber. The top in turn aids the current to deflect downwardly toward the outlet 5. In a drumlike chamber the wall of the chamber will facilitate the shaping of a more regular hollow cylinder than the rectangular chamber shown in the drawing.

A portion of the current directed toward the main outlet 5 is deflected through the auxiliary outlet 6 and the leakage therethrough is controlled by a damper 11. A damper 13 controls the outflow from the main outlet 5. By means of the dampers 11 and 13 the induced current in the gap 14 between the inlet 1 and the outlet 5 may be controlled.

That is to say, a. change in the adjustment of the outlet dampers in the main outlet and auxiliary outlet changes the number of revolutions that particles of the air currents make in the path of the currents about the house before they are allowed to escape. The particular advantage of this method is due to the fact that in each revolution a particular air particle of the air picks up an amount of moisture and the total amount of moisture picked up can be brought to practically the theoretical saturation point of the air by a proper adjustment of the outlet dampers. The substances to be dried ive up their moisture differently in air of diaerent degrees of saturation. Certain substances will give up moisture in highly saturated air, other substances require lower degrees of saturation of the air to give up their moisture. The higher the degree or percentage of saturation to which the air can be brought, the greater the efiieiency of the method.

It is, therefore, desirable to be able to adjust the number of revolutions of the partireadily in order to obtain the required percentage of saturation to suit the particular substance to be dried, by means of a very simple adjustment of dam ers in the main and the auxiliary outlets. ithout the auxiliary outlet 6 and the control between outlet 5 and auxiliary outlet 6, it would be necessary to change the width of the gap 14 each time it was desired to establish the proper number of whirls to achieve the maximum absor tion or efiicaciousness or capacity, but wit the arrangement shown, no changes are necessary except the readjustment of the flow of air through auxiliary outlet 6 and main outlet 5.

The nozzles 8 are fed from a tank 15 which contains the matter to be desiccated. The matter entering the nozzles is broken up by the air supplied to the nozzles through a conduit 16, by means of which the desired spray is formed within the chamber 3. If desired, pressure nozzles may be used to obtain the desired spray within the chamber 3. The velocity of the spray formed within the chamber is such that the same should not be strong enough to pass entirely across the air currents forming the hollow cylinder. That is, it should not strike the wall opposite the nozzles.

It will be noted that the opposite layers of the air forming the hollow cylinder are moving in opposite directions, that is to say, within the spray chamber oppositely directed air currents are formed, through which air currents the substance to be desiccated is sprayed. In a vertical chamber, in which the inlets and the outlets are in horizontal planes, there will be a rising and descending current, as shown in the drawing. The entering spray attacks the descending current first before it can enter the ascending current. The descending current has been in contact with particles of the spray that cross the hollow cylinder, and therefore its drying effect upon the spray is not of a character to cause crust formation on said particles, due to the fact that the said descending current carries already some moisture due to its contact with the particles of spray that have been attacked by the ascending current, which is the hotter and drier of the two and which becomes Ill the descending current as it continues its movement within the spray chamber.

lit will therefore be seen that in my method for spray drying the hottest or driest air contacts with that part of the spray which has already been in contact with air not so hot or dry. That is, the hottest or driest air in my arrangement acts on particles of the spray partially dried, in consequence, case hardening of the particles is prevented. Further, the air that has already absorbed some of the moisture from the particles and that carries dust is washed by the fresh spray entering the drier as it approaches the exit and increases the size of the particles dried.

It is to be remarked that by varying the leakage through the auxiliary outlet 6 the hollow of the cylinder may be varied in size. That is to say, the descending current is brought nearer to the wall in which the inlet and the nozzles are located by increasing the leakage through the auxiliary outlet 6. In other words, the two oppositely moving currents may be brought further apart by increasing the leakage through the auxiliary outlet 6. By stopping the leakage through the auxiliary outlet 6, the descending current may be moved a considerable distance away from the wall carrying the nozzles. It must be understood that the total air taken out from the main outlet 5 and the auxiliary outlet 6 is constant when the flow from the inlet 4 is constant.

ll claim:

1. A method of desiccation which consists in creating oppositely-directed continuous air currents, intersecting the said oppositely-directed currents by a spray of material to be desiccated and removing portions of the current that reacted with the spray successively. I

2. A method of desiccation which consists in creating a continuous current having oppositely-directed portions, intersecting the oppositely-directed portions of the current by a spray of material to be desiccated so that the spray enters that portion of the current which is further advanced, and removing in two successive places portions of the air current that reacted with the spray.

3. A method of desiccation which consists in creating continuous interconnected ascending and descending air currents forcing a spray of material to be desiccated through the ascending and descending currents, and removing at two different levels portions of the descending current that have reacted already with the spray.

4. A method of desiccation which consists in creating a continuous curvilinear air current portions of which move in opposite directions, forcing a spray of material to be desiccated through the oppositely moving portions of the current from the outside of said current, and removing in two successive places portions of theair current that have reacted with the spray.

5. A methodof desiccation which consists in creating a continuous air current in the form of a hollow cylinder, forcing a spray of substance to be desiccated through the cylinder, and removing in two successive places portions of the air current that have reacted with the spray.

6. A method of desiccation which consists in creating a continuous air current in the form of a hollow cylinder, forcing a spray of substance to be desiccated from the outside of the cylinder in a plane parallel to the elements of the cylinder and in a direction perpendicular to said elements, and removing in two successive places portions of the air current that have reacted with the spray.

7. A method of desiccation which consists in creating an air current in the form of a hollow cylinder, forcing an atomized substance to be desiccated through the cylinder from the outside of the said cylinder in a plane parallel to the elements of the said cylinder and in a direction perpendicular to said elements, and removing portions of the air current forming the hollow cylinder at places before and after where the spray enters the hollow cylinders.

8. A method of desiccation which consists in creating a continuous current having oppositely-directed portions, intersecting the oppositely-directed portions of the current by a spray of material to be desiccated, and removing portions of the current that reacted with the spray at places in the course of the current preceding and past the position where the spray entersthe currents.

WALTER L. FLEISHER. 

